1. Field of Invention
The invention relates to a buffer capacitor.
Capacitors are used to store electric charge and in doing so concentrates the charge at the ends of the positive plate and at the point of contact between the capacitor connector and the positive plate. These concentrated charges eventually build up and leak to the negative plate causing resistive heating and inducing inductance impairing the performance of the capacitor and can result in capacitor failure.
2. Prior Art
In attempts to reduce resistive heating and induced inductance various combinations of plate geometry and dielectric manipulations has been tried with limited success. One such attempt is by Charles C Rayburn U.S. Pat. No. 814,958. His capacitor is made from a plurality of plates, each plate being made of a thin film dielectric material, metallized on both sides and the plates and separating dielectric material are folded in a certain way and are laid in a staggered arrangement, whereby all the dielectric material is inside the electric field of the capacitor, after winding. This arrangement of plates and dielectric, improved the performance of the capacitor, but there is still the problem of the plate ends, where charge concentrates, leading to resistive heating and induced inductance, consequently like all current capacitors, it has limitations on its upper operational temperature usage, and the complex way in which the plates are folded, makes this capacitor more expensive manufacture.
Another attempt is the Slit-Foil Capacitor Application no. PCTGB/95/00213. This inventor simply made slits in the capacitor plate and the performance of the capacitor improved, but again, the ends of the plate still caused charge concentration, resulting in resistive heating and induce inductance, limiting the capacitor to an upper operational temperature limit. This capacitor requires the capacitor plates to be made with slits before it can be wound, thereby adding another element to manufacture, increasing manufacturing costs.
All currently available capacitors have upper operational temperature limitations due to resistive heating, showing clearly that resistive heating is still a significant problem in all capacitors in use in electronic and electrical applications. It is the view by experts in the capacitor industry, that resistive heating and induced inductance can be reduced, but cannot be eliminated completely.